Table of contents

1. A Review of General Chemistry5h 5m
2. Molecular Representations1h 14m
3. Acids and Bases2h 46m
4. Alkanes and Cycloalkanes4h 17m
5. Chirality3h 39m
6. Thermodynamics and Kinetics1h 22m
7. Substitution Reactions1h 48m
8. Elimination Reactions2h 30m
9. Alkenes and Alkynes2h 9m
10. Addition Reactions3h 19m
11. Radical Reactions1h 58m
12. Alcohols, Ethers, Epoxides and Thiols2h 42m
13. Alcohols and Carbonyl Compounds2h 17m
14. Synthetic Techniques1h 26m
15. Analytical Techniques:IR, NMR, Mass Spect7h 3m
16. Conjugated Systems6h 13m
17. Ultraviolet Spectroscopy51m
18. Aromaticity2h 34m
19. Reactions of Aromatics: EAS and Beyond5h 1m
20. Phenols55m
21. Aldehydes and Ketones: Nucleophilic Addition4h 56m
22. Carboxylic Acid Derivatives: NAS2h 51m
23. The Chemistry of Thioesters, Phophate Ester and Phosphate Anhydrides1h 10m
24. Enolate Chemistry: Reactions at the Alpha-Carbon1h 53m
25. Condensation Chemistry2h 9m
26. Amines1h 43m
27. Heterocycles2h 0m
28. Carbohydrates5h 53m
29. Amino Acids4h 20m
30. Peptides and Proteins2h 42m
31. Catalysis in Organic Reactions1h 30m
32. Lipids 2h 50m
33. The Organic Chemistry of Metabolic Pathways2h 52m
34. Nucleic Acids1h 32m
35. Transition Metals6h 14m
36. Synthetic Polymers1h 49m

28. Carbohydrates

Monosaccharide

Organic Chemistry

28. Carbohydrates

Monosaccharide

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4:19 minutes

Problem 48d,e

Textbook Question

Use Figure 23-3 (the D family of aldoses) to name the following aldoses.
(d) the enantiomer of D-galactose
(e) the C5 epimer of D-glucose

Verified step by step guidance

Identify the structure of D-galactose from Figure 23-3. D-galactose is an aldohexose with the specific configuration of hydroxyl groups on its chiral centers.

To find the enantiomer of D-galactose, invert the configuration at every chiral center. This means if a hydroxyl group is on the right in D-galactose, it should be on the left in its enantiomer, and vice versa.

Name the enantiomer of D-galactose. Since enantiomers are mirror images, the enantiomer of D-galactose is L-galactose.

Identify the structure of D-glucose from Figure 23-3. D-glucose is also an aldohexose with its own specific configuration of hydroxyl groups.

To find the C5 epimer of D-glucose, change the configuration of the hydroxyl group at the C5 position only, while keeping the rest of the molecule the same. The C5 epimer of D-glucose is D-mannose.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Aldoses

Aldoses are a type of monosaccharide characterized by the presence of an aldehyde group (-CHO) at one end of the molecule. They can exist in various forms, including D and L configurations, which refer to the orientation of the hydroxyl group on the chiral carbon farthest from the aldehyde. Understanding aldoses is crucial for identifying their structural relationships and naming conventions.

Enantiomers

Enantiomers are a pair of molecules that are non-superimposable mirror images of each other. In the context of sugars, D-galactose and its enantiomer, L-galactose, differ in the configuration around all chiral centers. Recognizing enantiomers is essential for naming aldoses correctly, as it affects their biochemical properties and interactions.

Epimers

Epimers are a specific type of diastereomer that differ in configuration at only one of several chiral centers. For example, D-glucose and D-mannose are C2 epimers, while D-glucose and D-galactose are C4 epimers. Identifying epimers is important for understanding the structural diversity of sugars and their relationships, particularly when naming aldoses based on their stereochemistry.

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